A dramatic 911 call by a 12-year-old hero, tony buke heard his little sister crying for help. His split-second decision to take action saved her life. Linsey davis has the details. Reporter: In the 911 call, you can hear tony's terror and resolve. My sister, samantha. She was standing on the ice. Okay. And she fell in. Reporter: The 12-year-old's call for help and the dramatic rescue that fold began saturday afternoon, when tony's 8-year-old sister fell through what she mistook for a prosen pond in their backyard. What he did next has many in ft. Wayne, indiana, calling him a hero. He dashes across the ice, cra cracking beneath his feet. He tries to get his sister to float on her back. At this point, she's unconsiders. I put my arm under her shoulders. I realized that wasn't going work. I grabbed her coat hood. I thought I wasn't going to survive. Because I was so cold. Their dad rushes to the pond and then he false in, too. But somehow, he imagimanages to thrash a path and pull tony to shore. He treaded water that whole time with one han and never let go of her. Reporter: By this time, his sister, sammy, isn't breathing. He mustered the strength to get to the house and call for help. While the ems is credited with reviving sammy, this morning, her big brother is being called a hero. He says he's not a hero. He's mine, and his sister's. Reporter: Tony says the label doesn't matter. I don't want to have glory and stuff. Reporter: He just wants to be known as someone who saved his sister. For "good morning america," linsey davis, abc news, new york. And we do know him for that. The split-second thinking. Let's get another check of

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